The volume of diffraction data that can be collected during an experimental session on modern synchrotron-based Macromolecular Crystallography (MX) beamlines equipped with fast readout photon-counting pixel detectors and the rate at which it can be collected means it is currently difficult (or impossible) for users to manually process, during the experiment, all data sets collected. To help remedy this situation and to provide the at-beamline feedback that is sometimes necessary for a successful experiment 'autoprocessing' software is often deployed with the results of automatic integration, scaling merging and reduction for individual data sets displayed in Laboratory Information Management Systems (LIMS) such as ISPyB from where they can also be downloaded. While the 'autoprocessing' approach works (i.e. provides data of sufficient quality for structure solution and refinement) in the vast majority of cases there is an increasing need for the post-experiment processing of raw diffraction images. In such cases the correct metadata for each dataset are essential to ensure the best results. For MX diffraction data collected at the ESRF this is stored in ISPyB, in the headers of the raw data images themselves and in automatically generated input files for the two main packages - XDS and MOSFLM - routinely used in the processing of ESRF-collected MX diffraction data. During my talk I will review the metadata currently logged during MX experiments at ESRF and look forward to what further metadata might be required when, either for validation purposes or the testing of new data processing and analysis protocols, raw data images are routinely made available to the wider scientific community.